Recording medium, wobble cycle detection method, wobble information detection method, wobble information detection circuit, and information recording/reproduction device

ABSTRACT

The present invention is structured so that a track of a recording medium is divided into a carrier wave area that is continuously wobbled by a carrier wave wobble of a specific carrier wave cycle, and an address area that is wobbled by a special wobble that has a cycle different from the carrier wave wobble and a phase determined in response to data  0  and data  1  of information stored by a wobble.

TECHNICAL FIELD

The present invention relates to a recording medium, such as a phasechange type, a write-once-read many type or an magneto-optical type, awobble cycle detection method and a wobble information cycle detectionmethod with respect to the recording medium, a wobble informationdetection circuit for detecting wobble information from the recordingmedium and an information recording and reproduction apparatus.

BACKGROUND ART

A track is formed in a recording area on a recording medium (opticaldisc) such as a DVD+R disc, a DVD+RW disc, etc. The track plays a roleof a guidance groove for a spot of a laser light irradiated forrecording and reproduction of information.

The wobble (meandering) is formed in the track, and since a wobblesignal detected from the wobble has a substantially fixed cycle, thedetected wobble signal is mainly used as rotating-speed information.

Moreover, information other than the above-mentioned rotating-speedinformation may also be stored in the track by modulating the wobble.

As information stored by the wobble, address information indicative ofan absolute position on a recording medium is most popular.

Additionally, there are listed a recording type indicative of feature ofthe recording medium, that is, a size of the recording medium or whetherthe recording medium is a write-once-read many type or an overwritetype, information of recording property, that is, parameters such as anoptimum recording power, a recording waveform or the like, andinformation such as a manufacture's name.

Next, a description will be given of a format of the wobble of each ofCD system recording media (CD-R disc, CD-RW disc, etc.) and DVD+ systemrecording media (DVD+R disc, DVD+RW disc, etc.).

The CD system recording medium: biphase-modulating address informationand wobbling a track with a frequency modulation based on it (forexample, refer to Japanese Laid-Open Patent Application No. 9-212871).

Specifically, in the CD system recording medium, two kinds frequenciesof 22.05 kHz±k Hz are assigned to data o and data 1, respectively, so asto record information using the wobble of about 10 cycles for one bit.Moreover, probabilities of generation of the data 0 and the data 1 arecaused to be substantially equal to each other so as to detect a clocksignal from 22.05 kHz, which is the center frequency.

The DVD+system recording medium: phase-modulating address informationand wobbling a track base on it.

In the DVD+ system recording medium, a carrier component is extractedfrom a carrier wave wobble of a carrier wave area, which occupies alarge part so as to detect a clock signal. The address information isrecorded in an address area by setting a wobble of the same phase withthe carrier wobble as data 0 and setting a wobble of a phase differentfrom the carrier wobble by 180 degrees as data 1.

However, there was a problem as shown below, respectively, in the wobbleof the CD system recording medium and the DVD+ system recording mediummentioned above.

In the format of the wobble of the CD system recording medium, since theclock signal of 22.05 kHz is extracted and a frequency differencerepresenting the data 0 and data 1 is extremely small as ±1 kHz, S/N ofthe signal was low and information recording quality was not good.Moreover, it is difficult to accurately specify a frequency changepoint, and there was a demerit that an absolute position accuracy waspoor.

On the other hand, in the format of the wobble of the DVD+ systemrecording medium, S/N of a signal can be raised by using a phasemodulation. Moreover, absolute position accuracy is also assured, and anadvance format has been achieved.

However, since the modulation methods of the wobble for synchronizationand the wobble for information are the same and the synchronizationsignal and the information signal are distinguished by a difference inthe phase inverted wobble length, it takes a time to pull-insynchronization. Moreover, since information is recorded by the samecycle and only the phase modulation, leakage of a wobble componentbetween adjacent tracks appears remarkably in degradation of informationsignal, and it was difficult to progress further high-densification ofnarrow track pitch while achieving both acquisition of reliability ofinformation and acquisition of recording quality.

DISCLOSURE OF THE INVENTION

It is a general object of the present invention to provide an improvedand useful recording medium, wobble cycle detection method, wobbleinformation detection circuit, and information recording andreproduction apparatus, in which the above-mentioned problems areeliminated.

A more specific object of the present invention is to suggest a wobbleformat that can acquire high-densification, high-reliability andstability in the future recording media, and also enables to detectwobble cycle and information according to the format.

In order to achieve the objects, a recording medium of the presentinvention is constituted so that a track is divided into a first areathat is continuously wobbled by a first wobble of a specific carrierwave cycle, and a second area that is wobbled by a second wobble thathas a cycle different from the above-mentioned first wobble and a phasedetermined in response to data 0 and data 1 of information stored by awobble.

Additionally, in order to achieve the objects, a wobble cycle detectionmethod of the present invention is constituted so as to multiply wobblesignals of the same signal obtained from wobbling of a track formed on arecording medium each other by a multiplier, and input a signal obtainedby an operation of the multiplication into a band pass filter of which apass band is set to about twice a frequency of a carrier wave so that acycle twice an output signal of the band pass filter is set to a cycleof the carrier wave of the wobble signal.

Additionally, in order to achieve the objects, a wobble informationdetection method of the present invention is constituted so as tocomprise a carrier wave processing procedure of extracting a frequencycomponent of the first wobble from the first area of the recordingmedium, a special wave processing procedure of extracting a phaseinformation component of the second wobble from the second area of theabove-mentioned recording medium, an information detecting procedure ofdetecting the information stored by the wobble from the phaseinformation component extracted by the above-mentioned special waveprocessing procedure based on the frequency component extracted by theabove-mentioned carrier wave processing procedure.

In order to achieve the objects, a wobble information detection circuitis constituted so as to comprise a wobble cycle detection circuit thatdetects a cycle of the carrier wave from a wobble signal obtained fromwobbling of the track formed on the recording medium, a clock signalgeneration circuit that generates a second clock signal of a twice cycleof the carrier wave based on the cycle of the carrier wave detected bythe wobble cycle detection circuit, and a special wave wobble detectioncircuit that indicates a position or a phase of the second wobble of theabove-mentioned second area based on the above-mentioned second clocksignal.

In order to achieve the objects, an information recording andreproduction apparatus of the present invention is constituted so as tobe mounted with the wobble information detection circuit, wherein anaccess is made to a target position of the above-mentioned recordingmedium based on information detected by the wobble information detectioncircuit so as to perform recording or reproduction of information on theabove-mentioned recording medium.

The recording medium, the wobble cycle detection method, the wobbleinformation detection method, the wobble information detection circuit,and the information recording and reproduction apparatus according tothe present invention can suggest a format of a wobble, which is capableof acquiring future high-densification, reliability and stability, on arecording medium, and can detect a cycle of a wobble and informationaccording to the format.

BRIEF DESCRIPTION OF DRAWINGS

Other objects, features and advantages of the present invention willbecome more apparent from the following detailed description when readin conjunction with the accompanied drawings.

FIG. 1 is an illustration showing a structure of a general recordingmedia that is also applicable to a mode for carrying out the presentinvention.

FIG. 2 is an illustration for explaining a phenomenon in which anamplitude of a wobble signal is fluctuated in a recording mediumaccording to an embodiment of the present invention.

FIG. 3 is an illustration for explaining a format of a wobble formed ona track of a recording media according to a first embodiment through afourth embodiment of the present invention.

FIG. 4 is also an illustration for explaining the format of the wobbleformed on the track of the recording media according to the firstembodiment through the fourth embodiment of the present invention.

FIG. 5 is an illustration showing an example of a wobble form in whichbit 0 representing data 0 and bit 1 representing data 1 aredistinguished in the recording medium according to the embodiments ofthe present invention.

FIG. 6 is a waveform chart showing an example of a wobble waveform inwhich a multiple of a cycle of a carrier wave wobble as an example of aspecial wave wobble of the recording media according to the embodimentsof the present invention.

FIG. 7 is a waveform chart showing a wobble waveform in a case where acycle of the special wave wobble is changed in its length as twice thecarrier wave wobble in the recording medium according to the embodimentsof the present invention.

FIG. 8 is an illustration for explaining a format of a wobble formed ona track of recording media according to an eighth through tenthembodiments of the present invention.

FIG. 9 is also an illustration for explaining the format of the wobbleformed on the track of the recording media according to the eighth totenth embodiments of the present invention.

FIG. 10 is also an illustration for explaining the format of the wobbleformed on the track of the recording media according to the eighth totenth embodiments of the present invention.

FIG. 11 is an illustration for explaining a format of a wobble formed ona track of a recording medium according to a fourteenth embodiment ofthe present invention.

FIG. 12 is an illustration showing waveforms of the wobbles provided ina carrier wave area, an address area and a synchronization area of therecording media according to the embodiments of the present invention.

FIG. 13 is an illustration showing a form of a wobble and a waveform ofa signal detected by the wobble in recording media according to aneleventh and twelfth embodiments of the present invention.

FIG. 14 is a block diagram showing a structured of a wobblesynchronization detection circuit that realizes a wobble synchronizationdetection method according to a twenty-fourth embodiment of the presentinvention and a structure of a wobble synchronization detection circuitas a background art.

FIG. 15 is a waveform chart showing signal waveforms of a wobble signalinput to a multiplier 32 shown in FIG. 14 and an output signal thereof.

FIG. 16 is an illustration showing a format of a track of recordingmedia according to a thirteenth embodiment and a fourteenth embodimentaccording to the present invention.

FIG. 17 is an illustration showing wobble forms in two kinds ofsynchronization areas of the recording medium according to theembodiments of the present invention.

FIG. 18 is an illustration showing a format and a wobble form in twokinds of synchronization areas of the recording media according to thethirteenth embodiment and the fourteenth embodiment of the presentinvention.

FIG. 19 is an illustration for explaining a specific example of a wobblemodulation in recording media according to a nineteenth embodimentthrough a twenty-first embodiment of the present invention.

FIG. 20 is also an illustration for explaining the specific example ofthe wobble modulation in the recording media according to the nineteenthembodiment through the twenty-first embodiment of the present invention.

FIG. 21 is also an illustration for explaining the specific example ofthe wobble modulation in the recording media according to the nineteenthembodiment through the twenty-first embodiment of the present invention.

FIG. 22 is a block diagram of a wobble information detection circuitaccording to a thirtieth embodiment through a thirty-fifth embodiment ofthe present invention.

FIG. 23 is a waveform chart showing an output waveform of each circuitwhen reproducing the recording medium of the wobble format of the type 1shown in FIG. 12 in the wobble information detection circuit shown inFIG. 22.

FIG. 24 is a waveform chart showing a waveform of an output signal ofeach part when demodulating using a SIN wave signal of conditions of aphase of 0 degree and a phase of 180 degrees in the wobble informationdetection circuit shown in FIG. 22.

FIG. 25 is an illustration for explaining a format of recording mediaaccording to the fifteenth embodiment and the sixteenth embodiment ofthe present invention.

FIG. 26 is an illustration for explaining a simplest method for checkinga phase state in wobble information detection circuits according to athirty-second embodiment and a thirty-third embodiment of the presentinvention.

FIG. 27 is a waveform chart showing an example of a wobble form of theformat of the recording medium according to eighteenth embodiment of thepresent invention.

FIG. 28 is a waveform chart showing a signal waveform when demodulatingthe wobble form of the type A in FIG. 27.

FIG. 29 is a block diagram showing a structure of information recordingand reproduction apparatuses according to a thirty-sixth embodiment anda thirty-seventh embodiment of the present invention.

FIG. 30 is an illustration for explaining detection of a wobble signalfrom a light-receiving element 94 through an arithmetic circuit of FIG.29.

FIG. 31 is a block diagram of a conceptualized wobble informationdetection circuit shown in FIG. 22.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereafter, a description will be given, based on the drawings, of thebest mode for carrying out the invention.

FIG. 1 is an illustration showing a structure of a general recordingmedium applicable also to a mode for carrying out the present invention.

The recording medium 1 is an optical disc, such as a DVD+R disc, aDVD+RW disc, etc, and as shown in (a) of FIG. 1, a track 2 is formed inthe form of concentric circles or spiral on a recording surface. Thetrack 2 consists of a groove 3 and a land 4, as shown in (b) of FIG. 1.

The track 2 is formed beforehand by a recording medium formingapparatus, and a recording apparatus records and reproduces informationalong the track of the recording medium.

Moreover, as rotation information, the groove 3 of the track 2 wobbles(meandering) in the recording medium so that a signal of a fixedfrequency (fixed cycle) can be detected when it rotates at a constantlinear velocity or a constant angular velocity. This wobbled portion isreferred to as a wobble.

In a CD-R disc, a CD-RW disc, a DVD+R disc or a DVD+RW disc, informationsuch as addresses is recorded by providing a part, which slightlychanges a frequency or a phase, while the wobble of he track 2 isregarded as having substantially fixed frequency.

Moreover, although the form of the wobble has the form of a usual waveas shown in (a) of FIG. 1 in many cases, it is necessary to derive onlya carrier wave component, and may be a in a saw form, a triangularwaveform or a trapezoid form, etc.

Transmission of information by changing the frequency or the phase ofthe above-mentioned wobble is well practiced in the communication field.In communication, since a standard frequency used at a transmitting endand a receiving end is fixed so that many channels can be used, acarrier wave component can be produced using an oscillator output, whichhas less frequency fluctuation.

Of course, although there is a case in which the carrier wave componentis extracted from a transmitted signal, it is merely a fine-tuning and afrequency does not change during a communication. Furthermore, althoughthere is an external disturbance (noise) in the properties of thecommunication path, an external disturbance does not leak in with thesame band as the frequency band used in the communication.

On the other hand, there is a difference with respect to the above pointin a recording medium such as an optical disc. Although a control tomaintain a constant rotation is performed in a recording medium, it isrequired to use a motor having a low stability of rotation so as toprogress a weight reduction and a minimization of the apparatus.Accordingly, the recording medium is unstable in its rotation, and alinear velocity changes.

Therefore, it is necessary to extract a carrier wave component form,which serves as a reference, from the wobble on the recording medium,and it is necessary to enables a demodulation of information, whichfollows a change in a linear velocity due to a fluctuation in rotation.

Another large difference is that there is leak-in of a fixed noise in acarrier wave band of the wobble. Since an interval between tracks on therecording medium is reduced and narrower tan a diameter of a light spotso as to increase a recording density at maximum, an end of the lightspot overlaps with the wobble of the adjacent track. Therefore, thewobble component of an adjacent track leaks in (this is refereed to as“cross-talk”). This means that an external disturbance of the same bandas a signal to be demodulated leaks in. Under such a circumstance, thewobble signal detected fluctuates due to influences thereof.

FIG. 2 is an illustration for explaining a phenomenon of fluctuation inan amplitude of a wobble signal in a recording medium. Since the signalscancel each other as shown in (a) of FIG. 2 when the wobble of the track2 a (referred to as “target track”) on which a light spot SP isirradiated and the wobbles of the adjacent tracks 2 b and 2 c have thesame phase, an amplitude of the wobble signal of the wobble detected byirradiation of the light spot SP is reduced.

On the other hand, since the signals are intensified each other as shownin (b) of FIG. 2 when the wobble of the track 2 d on which the lightspot is irradiated and the wobbles of the adjacent tracks 2 e and 2 fare reverse phase, an amplitude of the wobble signal of the wobbledetected by the irradiation of the light spot is increased.

That is, although there is no concept of a cross-talk in thecommunication field and a transmission close to a theoretical limit, inwhich an external noise is calculated as random, merely an extremely lowsignal quality is acquired by a system using the wobble of a recordingmedium.

For example, in the DVD+R/RW format of the optical disc, two-phase phasemodulation method was adopted so as to acquire higher stability ofinformation detection even with such a low quality.

However, in a synchronization signal which reverses a phase by 180degrees as a synchronization wobble, only the reversed portion has awobble signal characteristic reversed from an adjacent carrier wavewobble.

It should be noted that since a large part of the wobble is a carrierwave wobble, the cross-talk component is also considered as a carrierwave component. Specifically, if the carrier wave wobble portion of atarget track has a phase reversed from the adjacent wobble, an amplitudeof a large part of the detected wobble signal is large. However, sinceonly the synchronization wobble portion having the reversed phase is inthe same phase condition, they cancel each other and the amplitudebecomes small.

Therefore, according to the phase modulation with the carrier wavecycle, a demodulation result greatly fluctuates due to bad influences ofthe cross-talk, and S/N is deteriorated. In the DVD+ system, since notonly the synchronization information but also address information andrecording-medium information were stored by this phase modulationmethod, an information demodulation performance was slightly low.However, since the synchronization information has a constant cycle, itwas able to interpolate even if the demodulation performance is somewhatlow.

That is, a modulation method is needed, which is especially strong withrespect to the cross-talk, which has not been considered as a problem inthe communication field.

FIG. 3 and FIG. 4 are illustrations for explaining a format of thewobble formed on the track of a recording medium according to a firstembodiment through fourth embodiment of the present invention.

As shown in both FIG. 3 and FIG. 4, the carrier wave area (hereinafter,may be referred to as “first area”) 10 that occupies a large part of thearea in the track and an address area (hereinafter, may be referred toas “second area” that is a part of the area.

The carrier wave area 10 is wobbled continuously by the carrier wavewobble (hereinafter, referred to as “first wobble”) that causes todetect a wobble signal having a fixed cycle and a fixed phase.

In the carrier wave area 10, since a stable wobble signal is detectable,it is used for generation of a clock. In the detection of the wobble,since not only the above-mentioned cross-talk but also the recordedinformation component recorded by a user becomes a noise, a frequencyseparation from this is required.

Although it cannot be defined generally since it depends on a detectioncircuit system, the cycle of the carrier wave wobble is generally about20 to 200 times the record information reference clock cycle.

Additionally, if it is longer than that (frequency is low), the wobbledetection cannot be performed since it approaches a control band of aservo system that controls to locate a detection point (spot) to adesired position on the track.

In order to record address information, the address area 11 requires twokinds of wobble forms representing “0” (hereinafter, may be referred toas “data 0” and “1” (hereinafter, may be referred to as “data 1”).

In the recording medium according to the first embodiment, the addressarea 11 is subject to wobbling by a special wave wobble (hereinafter,may be referred to as “second wobble”) that causes to detect a specialwave wobble signal (hereinafter, may be referred to as “second wobblesignal”) that has a cycle different from the carrier wave wobble signal(hereinafter, may be referred to as “first wobble signal”) detected by acarrier waver wobble (hereinafter, may be referred to as “first wobble”)14 and has different phases with respect to the data 0 and the data 1 ofinformation to be stored.

In the recording medium according to the second embodiment, as shown inFIG. 3, the address area 11 is subject to wobbling by a special wavewobble 12 that causes to detect a special wave wobble signal that has acycle different from the carrier wave wobble signal detected by acarrier waver wobble 14 and has a phase corresponding to the data 0 ofinformation to be stored. Or, it is subject to wobbling by a specialwave wobble 13 that causes to detect a special wave wobble signal thathas a cycle different from the carrier wave wobble signal detected bythe carrier waver wobble 14 and has a phase corresponding to the data 1of information to be stored.

That is, the address area 11 is subjected to wobbling by the specialwave wobbles 12 and 13 that cause to detect wobble signal that has acycle different from the first wobble signal detected by the carrierwave wobble 14 and has different phases with respect to the data 0 andthe data 1 of the information to be stored. Thus, although it is easiestto assign a phase of 0 degree to the data 0 and a phase of 180 degreesto the data 1 when differentiating the phase of the special wave wobbleby 180 degrees in accordance with the information (when assigning phasesdifferent from each other by 180 degrees), of course, 90 degrees may beassigned to the data 0 and 270 degrees may be assigned to the data 1.

Additionally, as shown in FIG. 4, the address area 11 may be subjectedto wobbling by a combination of the carrier waver wobble 14 and thespecial wave wobble that causes to detect a special wobble signal thathas a cycle different from the carrier wave wobble signal detected bythe carrier wave wobble 14 and has different phases with respect to thedata 0 and the data 1 of the information to be stored. In the figure, anexample is indicated of a case of the special wave wobble 12 that causesto detect the special wave wobble signal having the phase correspondingto data 0 of the information to be stored.

Moreover, in the recording medium of the third embodiment, thegenerating position is caused to be different between the special wavewobble 12 corresponding to the data 0 of the above-mentioned informationand the special wave wobble corresponding to the data 1.

Furthermore, in the recording medium of the fourth embodiment, thegenerating position is caused to be different between the special wavewobble 12 corresponding to the data 0 of the above-mentioned informationand the special wave wobble corresponding to the data 1 relatively toeach other by a cycle thereof.

Moreover, in the recording medium of the fifth embodiment, the cycle ofthe above-mentioned special wave wobble is set to an integral multipleof the cycle of the above-mentioned carrier wave wobble. Therefore, thecycle of the special wave wobble signal detected by the special wavewobble becomes an integral multiple of the cycle of the carrier wavewobble signal detected by the above-mentioned carrier wave wobble.

Furthermore, in the recording medium of the sixth embodiment, the cycleof the above-mentioned special wave wobble is set to twice the cycle ofthe above-mentioned carrier wave wobble. Therefore, the cycle of thespecial wave wobble signal detected by the special wave wobble becomestwice the cycle of the carrier wave wobble signal detected by theabove-mentioned carrier wave wobble.

Moreover, in the recording medium of the seventh embodiment, the lengthof the above-mentioned special wave wobble is set to twice the cycle ofthe above-mentioned carrier wave wobble. Therefore, the length of thespecial wave wobble signal detected by the special wave wobble becomestwice the length of the carrier wave wobble signal detected by theabove-mentioned carrier wave wobble.

FIG. 5 is an illustration showing an example of a wobble form whichdistinguishes bit 0 representing the data 0 and bit 1 representing thedata 1. (a) of FIG. 5 is an illustration representing the relativepositions with respect to the carrier wave wobble cycle on the track asa reference by #0 through #8.

(b) of FIG. 5 shows an example of a wobble form which distinguishes thebit 0 representing the data 0 and the bit 1 representing the data 1 whenthe information is given to the position of the special wave wobble. (c)of FIG. 5 shows an example of a wobble form which distinguishes the bit0 representing the data 0 and the bit 1 representing the data 1 when theinformation is given to the position of the special wave wobble.

(d) of FIG. 5 shows an example of a wobble form which distinguishes thebit 0 representing the data 0 and the bit 1 representing the data 1 whenthe information is given to the position and phase of the special wavewobble.

Here, there is shown a case of the wobble form having twice the cycle ofthe carrier wave wobble (twice the cycle of the carrier waver wobblesignal) and having twice the length of the carrier waver wobble (twicethe length of the carrier wave wobble signal).

First, in the wobble form at the time of giving the information to theposition of the special wave wobble shown in (b) of FIG. 5, the carrierwave wobble is arranged at positions #1, #4, #5, #6, #7 and #8 on thetrack when the information stored in the track is the bit (Bit) 0 whichis data 0, and the special wave bobble 20, of which phase is continuousto the carrier wave wobble, is arranged at positions #2 and #3 on thetrack. Moreover, in the bit (Bit) 1 of the data 1, the carrier wavewobble is arranged at the positions #0, #1, #2, #3, #6, #7 and #8 on thetrack, and the special wave bobble 20, of which phase is continuous tothe carrier wave wobble, is located at positions #4 and #5 on the track.

As mentioned above, although the phase of the special wave wobble iscontinuous to the carrier wave wobble in both the cases of bit 0 and bit1, the information can be detected since the generating points of bothare different. Here, although the example of the case where thegenerating positions are changed between the bit 0 and bit 1, the bit 0and the bit 1 are distinguishable by wobbling one in which the specialwave wobble is arranged at positions #2 and #3 on the track and one inwhich they are do not arranged.

For example, it is distinguishable by determining a wobble signalvoltage at a timing corresponding to the phase of 90 degrees of thespecial wave wobble. However, since an amount of information increasesby changing the generating position of the special wave wobble, accuracycan be increased further.

Next, in the wobble form at the time of giving the information to theposition of the special wave wobble shown in (c) of FIG. 5, the carrierwave wobble is arranged at positions #0, #1, #4, #5, #6, #7 and #8 onthe track when the information stored in the track is the bit 0 which isdata 0, and the special wave bobble 20, of which phase is continuous tothe carrier wave wobble, is arranged at positions #2 and #3 on thetrack. Moreover, in the bit 1 of the data 1, the carrier wave wobble isarranged also at positions #0, #1, #4, #5, #6, #7 and #8 on the track,and the special wave bobble 21 having a phase different from the phaseof the special wave wobble 20 by 180 degrees is arranged at positions #2and #3 on the track. That is, the wobble in the recording medium of thefirst embodiment, the second embodiment, the fifth embodiment, the sixthembodiment and the seventh embodiment is shown.

Thus, although the generating position of the special wave wobble ismade the same by the case of the bit As mentioned above, by causing thegenerating positions of the special wave wobble to be the same in thecases of bit 0 and bit 1 but setting a reversed relationship between thebit 0 and the bit 1 by changing the phases of both by 180 degrees,high-quality information detection is allowed in the detection circuitmentioned later.

Next, in the wobble form at the time of giving the information to theposition of the special wave wobble shown in (d) of FIG. 5, the carrierwave wobble is arranged at positions #0, #1, #4, #5, #6, #7 and #8 onthe track when the information stored in the track is the bit 0 which isdata 0, and the special wave bobble 20, of which phase is continuous tothe carrier wave wobble, is arranged at positions #2 and #3 on thetrack. Moreover, in the bit 1 of the data 1, the carrier wave wobble isarranged also at positions #0, #1, #2, #3, #6, #7 and #8 on the track,and the special wave bobble 21 having a phase different from the phaseof the special wave wobble 20 by 180 degrees is arranged at positions #4and #5 on the track. That is, the wobble in the recording medium of thefirst embodiment, the third embodiment, the fourth embodiment, the fifthembodiment, the sixth embodiment and the seventh embodiment is shown.

Thus, since from #2 to #5 of the track are used by combining both theabove-mentioned position and phase, an amount of information isincreased and reliability can be improved by devising the demodulationcircuit.

Although all four cycles of the carrier wave wobble can also be used fortwo cycles of the special wave wobble in the similar manner as thatmentioned above, in such a case, the rate of the special wave wobble tothe whole increases, and the special wave wobble component will increasealso in the cross-talk. Since it is important for the effect using thespecial wave wobble of-double cycle that the cross-talk componentoccupies a large part of the carrier wave component, the special wavewobble should be reduced as much as possible. However, as long as thespecial wave wobble interval is sufficiently long, the special wavewobble can be two cycles since the problem becomes small.

Next, a description will be given further of the length of the cycle inthe recording medium of the fifth embodiment.

The FIG. 6 is a waveform chart showing a wobble waveform example as anexample of the above-mentioned special wave wobble in which it is anintegral multiple of the cycle of the carrier wave.

(a) of FIG. 6 shows the wobble form of the special wave wobble 22 havingthe wobble twice the cycle (two cycles) of the carrier wave wobble 14.

(b) of FIG. 6 shows the wobble form of the special wave wobble 23 havingthe wobble three times the (three cycles) of the carrier wave wobble 14.

(c) of FIG. 6 shows the wobble form of the special wave wobble 24 havingthe wobble four times the cycle (four cycles) of the carrier wave wobble14.

Moreover, FIG. 7 is a waveform chart showing the wobble waveform whenthe length of the cycle of the above-mentioned special wave wobble ischanged to twice the carrier wave wobble.

(a) of FIG. 7 shows the wobble form of the special wave wobble 25 beingset twice the cycle (tow cycles) of the carrier wave wobble 14 andhaving a wobble having a length equal to one cycle of the carrier wavewobble 14.

(b) of FIG. 7 shows the wobble form of the special wave wobble 26 beingset twice the cycle (tow cycles) of the carrier wave wobble 14 andhaving a wobble having a length equal to tow cycles of the carrier wavewobble 14.

(c) of FIG. 7 shows the wobble form of the special wave wobble 27 beingset twice the cycle (tow cycles) of the carrier wave wobble 14 andhaving a wobble having a length equal to three cycles of the carrierwave wobble 14.

(d) of FIG. 7 shows the wobble form of the special wave wobble 28 beingset twice the cycle (tow cycles) of the carrier wave wobble 14 andhaving a wobble having a length equal to four cycles of the carrier wavewobble 14.

Thus, if the cycle of the special wave wobble is made into an integralmultiple of the cycle of the carrier wave wobble, the influence ofcross-talk is avoidable and it will become easy to generate a referenceclock for demodulation from the clock generated form the special wavewobble.

Moreover, although one cycle of the special wave wobble may be assignedto the 1 bit of the information, two or more cycles may be assigned asmentioned above. However, since the amount of information storable inthe wobble will be reduced when the length of the 1 bit of theinformation is increased besides the above-mentioned problem, it shouldbe made as short as possible. Thus, twice the cycle (double cycle) andtwice the length of the carrier wave wobble are most effective.

Next, in the recording medium of the eighth embodiment, asynchronization area containing a synchronization wobble, which isdistinguishable from the above-mentioned carrier wave wobble and theabove-mentioned special wave wobble, is formed on the track.

Moreover, in the recording medium of the ninth embodiment, theabove-mentioned synchronization wobble is formed in a form having thesame cycle as the above-mentioned carrier wave wobble and a phasedifferent from the phase of the above-mentioned carrier wave wobble by180 degrees.

Furthermore, in the recording medium of the tenth embodiment, theabove-mentioned synchronization area is arranged on the trackimmediately before the above-mentioned address area.

Moreover, in the recording medium of the eleventh embodiment, theabove-mentioned carrier wave area is arranged immediately before theabove-mentioned synchronization area.

Further, in the recording medium of the twelfth embodiment, the lengthof the above-mentioned carrier wave area arranged immediately before theabove-mentioned synchronous area is set to a length five times or moreof the cycle of the above-mentioned carrier wave wobble.

Moreover, in the recording medium of the thirteenth embodiment, theabove-mentioned synchronization area is arranged at a fixed interval onthe track and the above-mentioned address area is arrangedintermittently and adjacent to the above-mentioned synchronization area.

Furthermore, in the recording medium of the fourteenth embodiment, thelength of the synchronization wobble of the above-mentionedsynchronization area arranged adjacent to the above-mentioned addressarea and the length of the synchronization wobble of the above-mentionedsynchronous area arranged independently apart from the above-mentionedaddress area are made different.

FIG. 8 through FIG. 10 are illustrations showing formats of the wobblesformed on the tracks of the recording media of the eighth embodiment tothe tenth embodiment, and parts that are common to FIG. 3 and FIG. 4 aregive the same reference numeral.

Formed on the tracks of the recording media of the eighth embodimentthrough the tenth embodiment are a carrier wave area (first area) 10which occupies a large part of the track, an address area (second area)11 which is a part, and a synchronization area 15 (hereinafter, may bereferred to as “boundary area” or “third area”) containing asynchronization wobble (hereinafter, may be referred to as “thirdwobble”) that is distinguishable from the carrier wave wobble wobbled inthe carrier wave area 10 and the special wave wobble wobbled in theaddress area 11.

The synchronization wobble signal detected from the synchronizationwobble in the synchronization area 15 is used as a synchronizationsignal indicative of a location (position) of the address area 11.

Therefore, the synchronization wobble contained in the synchronizationarea 15 is preferably has a form different from the carrier wave wobbleor the special wave wobble, and is distinguishable from these wobbles.

For example, as shown in the FIG. 8, it is preferable that thesynchronization wobble 16 in the recording media of the eighthembodiment through tenth embodiment is made to have a waveform havingthe same cycle as the carrier wave wobble 14, a length equal to onecycle of the carrier wave wobble 14, and a phase different from thephase of the carrier wave wobble 14 by 180 degrees. In this case, in thesynchronous area 11, the synchronization wobble 16 is arranged at thehead, and the carrier wave wobble 14 is arranged continuously afterthat.

Moreover, the generating position of the above-mentioned synchronizationwobble 16 may be changed. For example, the synchronization wobble 16 maybe arranged in the carrier wave wobble 14 in the synchronization area11, as shown in FIG. 9. It should be noted that an illustration is madeof a case where the special wobble 12 is used in the address area 12 ofthe figure.

Furthermore, as shown in (c) of FIG. 10, the synchronization wobble 16may be set to a length equal to two cycles of the carrier wave wobble.Anyway, the carrier wave wobble and the synchronization wobble shouldjust be distinguishable wobbles.

FIG. 11 is an illustration showing a format of the wobble formed on thetrack of the recoding media of the fourth embodiment of the presentinvention.

If tow kinds of synchronization wobbles are needed in the recordingmedium of the fourteenth embodiment, what is necessary is to use thesynchronization wobble 16 having the length equal to one cycle of thecarrier wave wobble and the synchronization wobble 16′ having a lengthequal to four cycles of the carrier wave wobble. Especially, if it isdistinguished by the same cycle but different length, the demodulationcircuit can be common and it is easy to grasp accurately a positionalrelationship with the address area. It should be noted that, withrespect to the special wave wobble in the view 11, as indicated in (d)and (e) of FIG. 11, the waveform in the recording media of the secondembodiment and the fourth embodiment is shown.

FIG. 12 is an illustration showing together waveforms of the wobbleprovided in the above-mentioned carrier wave area, the above-mentionedaddress area and the above-mentioned synchronization area.

FIG. 13 is an illustration showing a form of the wobble in the recordingmedium of the eleventh embodiment and the twelfth embodiment and awaveform of the signal detected by the wobble.

(b) of FIG. 13 shows a form of the wobble in which five cycles of thecarrier wave wobble 14 of the carrier wave area that are insertedbetween the synchronization wobble 16 of the synchronization area andthe special wave wobble 13 (or 12) of the address area.

Moreover, (c) of FIG. 13 shows a form of the wobble in which threecycles of the carrier wave wobble 14 of the carrier wave area that areinserted between the synchronization wobble 16 of the synchronizationarea and the special wave wobble 13 (or 12) of the address area.

Although, in order to extract a carrier wave wobble signal (carrier wavecomponent) by the carrier wave wobble from the wobble shown in FIG. 13,it is passed through a band pass filter (BPF), which cuts off anunnecessary noise, and the output of the BPF is binarized and sent tothe clock generation means, the signal is disordered in the modulationpart of the wobble. Although it depends on the characteristics of theBPF, the disorder occurs during several cycles of the carrier wave.

FIG. 14 is a block diagram showing a structure of a wobble cycledetection circuit, which realizes a wobble cycle detection method of atwenty-fourth embodiment of the present invention and a structure of awobble cycle detection circuit of a premise technology.

As shown in (a) of FIG. 14, the general wobble cycle detection circuitinputs the wobble signal into a band pass filter (BPF) 30, which has apass band of the wobble frequency (fw) of the wobble signal, andbinarizes the output signal by a binarizing circuit (COMP) 31 andtransfers to a PLL circuit of a subsequent stage. The PLL circuitgenerates a clock signal in synchronization with the wobble signal byeliminating high-frequency components. Due to the characteristics of theBPF 30, when a phase-modulation or frequency-modulation signal is inputsuch as the address area or the synchronization area shown in FIG. 13,disorder of the output corresponding to several cycles of the carrierwave wobble signal is generated, and the disorder gives bad influencesto the PLL circuit of the subsequent stage.

In the case of the wobble as shown in = of (c) of FIG. 13 (in the casewhere three cycles of the carrier wave wobble area inserted between thesynchronization wobble of the synchronization area and the special wavewobble of the address area), since the synchronization wobble and thespecial wave wobble are close to each other, the output of the BPF 30,which indicates the cycle of the carrier waver wobble, is continuouslydisordered, and, thereby the operation of the PLL circuit is unstableand the synchronization of the clock signal to the wobble signal tendsto collapse.

Thus, in the case of the general BPF 30, since the cycle is revitalizedafter three cycles of the carrier wave wobble, the signal indicative ofthe cycle of the carrier wave wobble is restored temporarily byinserting the carrier wave area corresponding to at least five cyclesbetween the synchronization area and the address area, therebystabilizing the operation of the PLL circuit.

FIG. 15 is a waveform chart showing the signal waveform of the wobblesignal input into the multiplier 32 shown in FIG. 14 and the outputsignal thereof.

As shown in (b) of FIG. 14, the wobble cycle detection circuit, whichrealizes the wobble cycle detection method of the twenty-fourthembodiment inputs the wobble signal (wobble signals indicated in (a) and(b) of FIG. 15, respectively). That is, the second power of the wobblesignal is calculated by the multiplier 32, and, as a result of themultiplication, a signal which does not have disorder in the phasemodulation part of the cycle of the carrier wave wobble can be extracted(refer to (c) of FIG. 15).

However, since the frequency becomes twice the wobble signal, the passband of the BPF 30 and the operational frequency of the PLL circuit aremade into twice, and are divided by two so as to be the clock of thecarrier wave wobble component. By using this, the unstable factor of theclock signal which is a problem due to the synchronization area and theaddress area being continuous is reduced, and there is no need to inserta long carrier wave area between the synchronization area and theaddress area.

In the recording medium of the thirteenth embodiment, theabove-mentioned synchronization area is arranged at a fixed interval onthe track and the above-mentioned address area is arrangedintermittently and close to the above-mentioned synchronization area.

Moreover, in the recording medium of the fourteenth embodiment, thelength of the synchronization wobble of the above-mentionedsynchronization area, which is arranged adjacent to the above-mentionedaddress area and the length of the synchronization wobble of theabove-mentioned synchronization area, which is arranged independentlyapart from the above-mentioned address area are made different.

FIG. 16 is an illustration for explaining a format of the track therecording media of the thirteenth embodiment and the fourteenthembodiment.

In the track of the recording media of the thirteenth embodiment and thefourteenth embodiment, as shown in (b) of FIG. 16, the synchronizationarea (area indicated as “sync” in the figure) 15 is arranged at a fixedinterval and the address area (area indicated as “AD” in the figure) 11is arranged intermittently and in the vicinity of the synchronizationarea 15. Moreover, as shown in (a) of FIG. 16, the synchronization area15 and the address area 11 may be arranged always adjacent to eachother.

For example, in a usual format in a recording medium, such as a DVD+Rdisc and a DVD+RW disc, as shown in (a) of FIG. 16, the synchronizationarea 15 and the address area 11 are made into a set, and are arrangesclose to each other. Although the address domain 11 contains mainlyaddress information, of course, information such as the characteristicsof the recording medium can also be provided if there is a room in anamount of information, and, therefore, it is necessary to insert itfrequently as much as possible.

However, from the area where the synchronization area 15 and the addressarea 11 are made into a set, only the signal having disordered cycle bythe wobble cycle detection circuit is detected. Therefore, in order toextract a stable clock signal from the carrier wave wobble, theinsertion frequency of the address area cannot be increased too much.

Although the disorder of the cycle in the synchronization area and theaddress area was mentioned, it is natural that, when the synchronizationarea, in which only one cycle of the wobble is phase modulated, isarranged independently, the disorder in the binary signal indicative ofthe wobble cycle is small and it can be almost eliminated by the clockgeneration circuit of the subsequent stage, and, thus, there in on badinfluence to the clock. If the synchronization area is arrangedfrequently, a time for initially finding the synchronization area isshort, and a phase comparison between a SIN wave signal (fw) and the SINwave signal (fw/2) can be performed frequently, as mentioned later, and,thus, it is possible to find a wobble shift early and perform acorrection thereof. Accordingly, it is preferable to frequently insertonly the synchronization area independently of the address area.

FIG. 17 is an illustration showing a wobble format in two kinds ofsynchronization area.

Moreover, an example in which a number of phase modulation wobbles ischanged, is shown in FIG. 17 as an example of a case where, as shown in(b) of FIG. 16, the wobble form is changed between the synchronizationarea (described as “sync area A” in the figure) 15 which makes a setwith the address area 11 and the synchronization area (described as“sync area B” in the figure) 15′ existing independently apart from theaddress area 11 and interposed between the carrier wave areas 10.

The number “x” in “#x” indicated in (a) of FIG. 17 is the number countedfor each cycle of the carrier wave wobble by setting a first wobble ofthe synchronization area 15 to number 0. In the synchronization area 15arranged in the set of the address area 11, it is preferable to performa phase-demodulation of one cycle of the carrier wave wobble of “#0”,that is, a demodulation of one wobble, so that an accurate wobbleposition can be determined.

However, in the independent synchronization area 15′, in order toprevent an erroneous detection due to a noise and for the purpose ofclearly indicate a brake point of the address information, the phasemodulation corresponding to two cycles of the carrier wave wobble, “#0”and “#1”, which are different from the synchronization area 15, that is,the modulation of two wobbles is made.

FIG. 18 is an illustration showing a format of the track of therecording media of the thirteenth embodiment and the fourteenthembodiment and a wobble form in two kinds of synchronization areas.

An example in which the address area 11 and the synchronous area 15 aremade into a set and arranged adjacent to each other is shown in (a) ofFIG. 18. Additionally, an example in which the synchronization area 15is arranged at a fixed interval and the address area 11 isintermittently arranged is shown in (b) of FIG. 18.

Although the address area 11 is arranged for each two synchronizationareas 15 and 15′, it is not limited to this, of course, and the rate ofarranging the synchronization area independently may be determined inaccordance with an amount of information stored in the address area, apull-in rate of synchronization using the synchronization area, and abreak point of the information stored in the wobble.

For example, if it is objects to improve the pull-in rate ofsynchronization and check of the wobble shift, the address area may bearranged at a frequency of equal to or less than ten synchronizationareas. Additionally, if it is a break point corresponding to theinformation stored in the wobble, insertion may be made for each 50-100.

The synchronization wobble of the synchronization area 15 immediatelybefore the address area 11 shown in (b) of FIG. 18 is a phase modulationof one cycle of the carrier wave wobble, and the synchronization wobbleof the synchronization area 15′ independently arranged is a phasemodulation of four cycles of the carrier wave wobble.

For example, if an improvement in the pull-in of synchronization or acheck of the wobble shift is an object, the synchronization areas ofequal to or smaller than 10 sets may be arranged between the addressareas. Although the insertion frequency of the address area isdetermined according to a necessary information amount, it is preferably50-100. This is because it is necessary to set to about ten times a sumof the lengths of the synchronization area and the address area inconsideration of stability of a case where the circuit for extractingthe clock from the carrier wave area is designed using general purposecircuit.

On the contrary, although the rate of the carrier wave area occupied toall wobbles is about 90 percent, it is set to be equal to or less than10 sets since 10 percent is maximum so as to store it by furtherincreasing the synchronization area Of course, it is necessary that thesynchronization area is as short as 1-2 wobbles and has a pattern thatdoes not give large influence to the operation of the clock generationcircuit. In the information such as a normal address according to thesynchronization area, several ten bits are a data break point.

The synchronization wobble 16 of the synchronization area 15 immediatelybefore the address area (AD area) 11 is phase modulation correspondingto one cycle of the carrier wave wobble 14, and the synchronizationwobble 16′ of the synchronization area 15′ arranged independently isphase modulation corresponding to four cycles of the carrier wave wobble14.

Next, in the recording medium of the nineteenth embodiment, formed inthe track are a carrier wave area wobbled continuously by a carrier wavewobble of a specific carrier wave cycle; a synchronization areacontaining a synchronization wobble having the same cycle as the carrierwave wobble and a phase different from the carrier wave wobble by 180degrees and having a length four times the specific carrier wave cycle;and an address area having a cycle twice the specific carrier wave cycleand consisting of a special wave wobble assigned to phases different by180 degrees in accordance with the data 0 and the data 1 of theinformation stored by the wobble, wherein the above-mentionedsynchronization area is arranged immediately before or adjacent to theabove-mentioned address area.

In the recording medium of the twentieth embodiment, the number ofwobbles between the above-mentioned synchronization areas is set to beequal to or greater than 60 as making the carrier wave as a reference.

In the recording medium of the twenty-first embodiment, formed in thetrack are a carrier wave area wobbled continuously by a carrier wavewobble of a specific carrier wave cycle; a synchronization areacontaining a synchronization wobble having the same cycle as the carrierwave wobble and a phase different from the carrier wave wobble by 180degrees and having a length four times the specific carrier wave cycle;and an address area having a cycle twice the cycle of the specificcarrier wave and a length twice the specific carrier wave and in whichthe relative generating position is set to a position separate by adistance twice the carrier wave cycle in accordance with the data 0 andthe data 1 of the information stored by the wobble and containingspecial wave wobbles assigned to phases different by 180 degrees andhaving a length four times the specific carrier wave cycle, wherein theabove-mentioned synchronization area is arranged immediately before oradjacent to the above-mentioned address area.

FIG. 19 through FIG. 21 are illustrations for explaining examples ofspecific wobble modulation in the recording media of the nineteenthembodiment to the twenty-first embodiment. Particularly, FIG. 20 is anillustration for explaining an example of specific wobble modulation inthe recording medium of the nineteenth embodiment, and FIG. 21 is anillustration for explaining an example of specific wobble modulation inthe recording medium the twenty-first embodiment.

As shown in (a) of FIG. 20, the address area (#4, #5) is insertedbetween the synchronization area (#0-#3) and the carrier wave area (#4,#5). This case in which the synchronization area is solely arranged isreferred to as a block sync (BlockSync), and, as shown in (b) of FIG.19, the synchronization wobble is made to phase modulation of a lengthof four cycles of the carrier wave wobble.

Moreover, the synchronization wobble of the synchronization areaarranged in the vicinity of the address area is set to a length of onecycle of the carrier wave wobble, and, in the address area, the wobblesuch as shown in (c) of FIG. 19 is assigned to the data 0 and the wobblesuch as shown in (d) of FIG. 19 is assigned to the data 1 by using thespecial wave wobble of twice the cycle of the carrier wave wobble.

FIG. 20 and FIG. 21 show formats of a case where the carrier wave areais not interposed between the synchronization area and the address area.

As shown in (a) of FIG. 20, the synchronization area (#3-#0) and theaddress area (#4, #5) are adjacent to each other, and the carrier wavearea (#4, #5) is partially inserted. The block sync (BlockSync) of thesynchronization area is the same as (b) of FIG. 19. Additionally, thesynchronization wobble of the synchronization area is set to a length ofone cycle of the carrier wave wobble, and, in the address area, thewobble such as shown in (c) of FIG. 20 is assigned to the data 0 and thewobble such as shown in (d) of FIG. 20 is assigned to the data 1 byusing the special wave wobble of twice the cycle of the carrier wavewobble. Additionally, the address area may be assigned to #4-#7 as shownin FIG. 21, the address area with respect to the data 0 may be assignedto #4 and #5 with respect to the data 0 as shown in (c) of FIG. 21, anda special wave wobble having a phase different from the above-mentionedspecial wave wobble may be assigned to #6 and #7 with respect to thedata 1 as shown in (d) of FIG. 21.

Moreover, in the recording medium of the twenty-second embodiment, thenumber of the wobbles between the above-mentioned synchronization areais set to be equal to or greater than 80 by making the carrier wavewobble as a reference.

Further, in the recording medium of the twenty-third embodiment, thesynchronization wobble of the above-mentioned synchronization area isset to one-cycle length and four-cycle length of the above-mentionedcarrier wave wobble, and the synchronization wobble arranged immediatelybefore or in the vicinity of the above-mentioned address area is set toone-cycle length of the above-mentioned carrier wave wobble, and othersare set to four-cycle length of the above-mentioned carrier wave wobble.

Next, a description will be given of an operation of the wobbleinformation detection circuit of the thirtieth embodiment throughthirty-fifth embodiment and a process of a wobble information detectionmethod of the twenty-fifth embodiment through twenty-ninth embodiment inthe wobble information detection circuit.

FIG. 22 is a block diagram showing a structure of the wobble informationdetection circuit of the thirtieth embodiment through the thirty-fifthembodiment.

FIG. 23 is a waveform chart showing output waveforms of each circuit ina case of reproducing the recording medium of a wobble format of thetype (Type) 1 shown in FIG. 12 in the wobble information detectioncircuit shown in FIG. 22.

In the wobble information detection circuit shown in FIG. 22, the wobbleinformation detection method of the twenty-fifth embodiment performs: acarrier wave process procedure of extracting a frequency component ofthe carrier wave wobble from the carrier wave area of the recordingmedium of the above-mentioned first embodiment through the fourteenthembodiment and embodiments mentioned later; a special wave processprocedure of extracting a phase information component of the specialwave wobble from the address area of the above-mentioned recordingmedium; and an information detection procedure of detecting theinformation stored by the wobble from a phase information componentextracted by the above-mentioned special wave process procedure based onthe frequency component extracted by the above-mentioned carrier waveprocess procedure.

In the wobble information detection circuit shown in FIG. 22, the wobbleinformation detection method of the twenty-sixth embodiment performs: acarrier wave process procedure of extracting a frequency component ofthe carrier wave wobble from the carrier wave area of the recordingmedium of the above-mentioned eighth embodiment through the fourteenthembodiment and embodiments mentioned later; a special wave processprocedure of extracting a phase information component of the specialwave wobble from the address area of the above-mentioned recordingmedium; a synchronization process procedure of extracting a phaseinformation component of the synchronization wobble from thesynchronization area of the above-mentioned recording media; and aninformation detection procedure of detecting information stored by thephase information components extracted by the above-mentioned specialwave process procedure and the above-mentioned synchronization processprocedure based on the frequency component extracted by theabove-mentioned carrier wave process procedure.

In the wobble information detection circuit shown in FIG. 22, the wobbleinformation detection method of the twenty-seventh embodiment performs:a carrier wave process procedure of extracting a frequency component ofthe carrier wave wobble from the carrier wave area of the recordingmedium of the above-mentioned first embodiment through the fourteenthembodiment and embodiments mentioned later and generating a clock of atleast twice the above-mentioned specific carrier wave cycle; a specialwave process procedure of extracting a phase information component fromthe address area of the above-mentioned recording medium based on aclock of at least twice the above-mentioned specific carrier wave cycle;and an information detection procedure of detecting information storedby the wobble from the phase information component extracted by thespecial wave process procedure.

In the wobble information detection circuit shown in FIG. 22, the wobbleinformation detection method of the twenty-eighth embodiment performs: acarrier wave process procedure of extracting a frequency component ofthe carrier wave wobble from the carrier wave area of the recordingmedium of the above-mentioned eighth embodiment through the fourteenthembodiment and embodiments mentioned later and generating clocks of theabove-mentioned specific carrier wave cycle and twice theabove-mentioned specific carrier wave cycle; a special wave processprocedure of extracting a phase information component from the addressarea of the above-mentioned recording medium based on at least the clockof twice the above-mentioned specific carrier wave cycle; asynchronization process procedure of extracting a phase informationcomponent of the synchronization wobble from the synchronization area ofthe above-mentioned recording media based on the clock of theabove-mentioned specific carrier wave cycle; and an informationdetection procedure of detecting information stored by the wobble fromthe phase information component extracted by the above-mentioned specialwave process procedure in the address area of which position isspecified based on the phase information component extracted by thesynchronization process procedure.

In the wobble information detection circuit shown in FIG. 22, the wobbleinformation detection method of the twenty-ninth embodiment performsboth a first demodulation for detecting a phase or a frequency of thewobble signal based on the clock of the above-mentioned specific carrierwave cycle in the above-mentioned address area and a second demodulationfor detecting he 2nd recovery which detects a phase or a frequency ofthe wobble signal based on the clock twice the above-mentioned specificcarrier wave cycle, and determines the data 0 and the data 1 of theinformation stored by the wobble.

As shown in FIG. 22, the carrier wave component of the wobble signal isextracted by a wobble cycle detection circuit 40 comprising a band passfilter (BPF) 41, which passes only the carrier wave component, and abinarizing circuit (COMP) 42. The wobble cycle detection circuit may usethe wobble cycle detection circuit, which realizes the wobble cycledetection method of the twenty-fourth embodiment.

The signal of the carrier wave component is input into a clockgeneration circuit 50, which is mainly comprising a phase locked loopcircuit (PLL circuit) 51, high frequency and low frequency componentsarea eliminated, and a fw/2 signal (second clock signal) of a frequency(double cycle) of a half of the fw signal is generated by the fw signal(first clock) of the wobble frequency which follows the carrier wavecomponent and a ½ frequency generation circuit 52.

Although the wobble signal is a signal of a fixed cycle ideally, sincethere is jitter (temporal fluctuation due to noise or fluctuation inrotation of a recording medium), the cycle of the carrier wave componentchanges delicately. A high-frequency component of this is eliminated bythe clock generation circuit 50 so as to follow the fluctuation in thelinear velocity.

On the other hand, the wobble signal is sent to a synchronization signaldetection circuit 60 and an address signal detection circuit 70 aftereliminating a low-frequency noise by a high pass filter (HPF) 70.

The synchronized signal detection circuit 60 detects mainly themodulated part of the cycle of the carrier wave wobble, such as thecarrier wave wobble contained in the carrier wave area and thesynchronization wobble contained in the synchronization area.

It can be used also for the demodulation of the carrier wave cycle partcontained to the address area.

Moreover, the address signal detection circuit 70 mainly detects amodulated part of twice the carrier wave frequency, such as the specialwave wobble of the address area, and it is not one which uses only theaddress information.

For example, if the fourth wobble mentioned later has a cycle twice thecarrier wave, it may be detected. If the synchronization wobble of thesynchronization area has a cycle twice the carrier wave wobble, it maybe detected. Moreover, although the clock signal having a cycle twicethe carrier wave wobble is generated by clock generation circuit 50 whenthe special wave wobble has a cycle twice the cycle of the carrier wavewobble, when it is other integral multiple, a clock signal of theintegral multiple is generated so as to be the second clock signal.

Moreover, the function to distinguish and adjust a phase of a polarityof the second clock signal may be given to the clock generation circuit50, or may be mounted separately.

If it is mounted separately, as a polarity determine circuit shown inFIG. 22, the phase of the second clock signal is distinguished based onthe a result of demodulation of the synchronization signal or the fourthwobble. According to the result, the polarity or the phase of the outputof the second clock signal of the clock generation circuit 50 may beadjusted or a process polarity in an address information process(illustration is omitted) in a subsequent stage.

In the synchronization signal detection circuit 60, while an unnecessaryhigh-frequency noise is removed by the low pass filter (LPF) 61, a SINcircuit 62 generates a SIN wave signal (fw signal) of the same cyclefrom the first clock signal, and a multiplication operation of theoutput signal of the LPF 61 and the SIN wave signal (fw) is carried outby a multiplier 63. The signal waveform is shown in (f) of FIG. 23.

(a)-(g) of FIG. 23 show waveforms of each part when demodulation isperformed with the SIN wave signal (fw) of the wobble carrier wave cyclein the synchronization signal detection circuit.

The number written as #x of the wobble number shown in (a) of FIG. 23 isa number which is counted for each carrier wave cycle by setting thehead wobble of the synchronization area as 0th for the sake ofexplanation, and the expected wobble number of (h) of FIG. 23 is anumber which is counted by setting a position to be detected as 0th inconsideration of a delay in the demodulation circuit.

Moreover, bold lines represent the phase modulated parts, and the boldlines represent a case of Data_0 and the dotted lines represent a caseof Data_1 in the address area.

Explaining a signal flow, the multiplication result of the wobble signaland the SIN wave signal (fw) is subjected to an integration operationfor each carrier wave cycle by an integrator (∫) 64, and is sampled by asample hold circuit (S/H) 65, and is held for a time of the carrier wavecycle.

In this case, when the output of the S/H 65 is changed to—side, itbecomes the synchronized signal. It should be noted that the integrationresult is zero in the second wobble of the double cycle.

The reset signal (Reset) of the integrator 63 and the sample signal(Sample) of the S/H 65 operate at a timing indicated by O in the outputsignal of the S/H 65 (refer to (f) of FIG. 23). Although it is generalto generate these by the clock generation circuit 50, the timing may beprocessed once by an address position signal generation circuit 81.Since there is a phase reversal part of the synchronization part in #0of the wobble signal, the address position signal for pinpointing theposition to #6 and #7, at which the synchronization wobble is generated,is output by the address position signal generation circuit 81 based onthe synchronization signal.

On the other hand, almost the same operation as the synchronizationsignal detection circuit 60 is performed also in the address signaldetection circuit 70.

However, the cycle of the SIN wave changes into the cycle of the secondclock signal. Explanation of the waveform here is shown in (h)-(1) ofthe FIG. 23.

In this case, although there is a part of the special wave wobble ofdouble cycle, which is the address information, in the wobble positionof #6 and #7, the output signal of the S/H 75 changes with a delaycorresponding to one cycle of the carrier wave wobble, and is changed toplus or minus in accordance with the phase of the special wave wobble,which indicates it is detectable. If the determination of the positionof the special wave wobble according to the position signal is notperformed, a discrimination of zero is also needed in addition to thedetermination of plus or minus since zero is detected in the carrierwave wobble or the synchronization wobble of the cycle of the carrierwave wobble. Although it is satisfactory in a non-recorded area withsufficient signal quality, it is disadvantageous for the determinationin a recorded area with many noise components. Therefore, it isdesirable to use the position signal so as to perform the plus or minusdetermination at the position where the special wave wobble exists.

Although the wobble information detection circuit shown in the FIG. 22is a demodulation circuit using a synchronization detection method, itmay be realized by a delay detection method of a well-known technologyin the communication field.

Moreover, although explained by the method of carrying out themultiplication of the SIN wave signal in analog in above-mentionedexplanation, the multiplication may be performed using a square wave of1, −1 instead of the SIN wave. Moreover, the wobble signal may bedigitized by an analog digital converter, and generation of the SIN wavemay be processed using data stored in a ROM.

In this case, it is desirable that the quantization speed be equal to orhigher than 8 times the wobble cycle, and the resolution be equal to orhigher than 5 bits.

FIG. 31 is a block diagram which conceptualizes the wobble informationdetection circuit shown in FIG. 22.

The information signal is extracted from the wobble signal and theinformation stored in the wobble of the recording medium can bereproduced by a carrier wave processing system 110, which has a functionof a combination of the wobble cycle detection circuit 40 shown in FIG.22 and the clock generation circuit 50, a synchronization processingsystem 111, which has a function of the address signal detection circuit70, and a special wave processing system 112, which has the function ofthe address signal detection circuit 70. It should be noted that thesynchronization processing system is not essential, and the data may bedetected by the special wave processing system 112, using the referencesignal obtained by the carrier wave processing system 110 and thefunction of the synchronization processing system may be substituted byprocessing the data.

Although the general phase demodulation method is explained in the waveforms shown in FIG. 23, if it is demodulated by the first clock signal(fw signal) of the carrier wave cycle, the phase and the frequency ofthe carrier wave component can be detected. However, this must be thefact that the cross-talk component of the carrier wave component is alsodetected. Since a large portion of the cross-talk is the carrier wavecomponent, the wobble signal is strengthened or weakened depending onwhether it is the same phase or reverse phase with the wobble phase ofthe target track, and this is reflected in the demodulation result as itis and causes a fluctuation. On the other hand, observing the waveformdemodulated by the second clock signal (fw/2 signal) of twice thecarrier wave cycle, the demodulation result is zero irrespective of thephase with respect to the wobble of the carrier wave component. That is,the cross-talk of the carrier wave component does not give influences tothe demodulation by the second clock signal.

Mathematically, it is proved as follows.

The wobble waveform is set to f (T). This condition is considered as thefollowing four.f(T)=sin(2T): Wobble of the carrier wave cycle   (I)f(T)=sin(2T)±0.2* sin(2T): Wobble of the carrier wave cycle+cross-talk(carrier wave component)   (II)f(T)=sin(T): Wobble of twice the carrier wave cycle   (III)f(T)=sin(T)±0.2* sin(2T): Wobble of twice the carrier wavecycle+cross-talk (carrier wave component)   (IV)

To these waveforms, the demodulation result can be obtained byintegrating after multiplying by sin(2T) in the case of demodulation (I,II) of the carrier wave cycle component, and by integrating aftermultiplying by sin(T) in the case of demodulation (III, IV) of thecarrier wave cycle component. The period of integration for both is0-2π, which corresponds to two cycles of the carrier wave, that is, onecycle of the second wobble.

A difference between presence and non-presence of cross-talk isinvestigated by comparing the results of (I) and (II) and (III) and(IV).

If it is set as 2T=x using a variable substitution method in thedemodulation of (I), T=x/2 and dT=dx/2, and the following equation 1 andequation 2 are obtained. $\begin{matrix}{{\int_{({0\rightarrow{2\pi}})}{{f(T)}*{\sin\left( {2T} \right)}\quad{\mathbb{d}T}}} = {{\int_{({0\rightarrow{2\pi}})}{\sin^{\Cap}2\left( {2T} \right)\quad{\mathbb{d}T}}} = {{1/2}*{\int_{({0\rightarrow{4\pi}})}{\sin^{\Cap}2(x)\quad{\mathbb{d}x}}}}}} & \left\lbrack {{equation}\quad 1} \right\rbrack \\{{\int_{({0\rightarrow{4\pi}})}{\sin^{\Cap}2(x)\quad{\mathbb{d}x}}} = {{\left\lbrack {{- {\sin(x)}}*{\cos(x)}} \right\rbrack_{({0\rightarrow{4\pi}})} + {\int_{({0\rightarrow{4\pi}})}{\cos^{\Cap}2(x)\quad{\mathbb{d}x}}}} = {{\left\lbrack {- {\sin\left( {2x} \right)}} \right\rbrack_{({0\rightarrow{4\pi}})} + {\int_{({0\rightarrow{4\pi}})}{\left( {1 - {\sin^{\Cap}2(x)}} \right){\mathbb{d}x}}}} = {{\int_{({0\rightarrow{4\pi}})}{\mathbb{d}x}} - {\int_{({0\rightarrow{4\pi}})}{\sin^{\Cap}2(x)\quad{\mathbb{d}x}}}}}}} & \left\lbrack {{equation}\quad 2} \right\rbrack\end{matrix}$

According to the equation 1 and equation 2, the following equation 3 isobtained. That is, it is equation 4. Thus, equation 5 is obtained.∫_((0→4π))sin ˆ2(x)d x=2 π  [equation 3]∫_((0→2π))sin ˆ2(2T)d T=π  [equation 4]∫_((0→2π)) f(T)*sin(2T)d T=π  [equation 5]

In the case of the demodulation of (II), equation 7 is obtained from thefollowing equation 6 and the above-mentioned equation 4. $\begin{matrix}{{\int_{({0\rightarrow{2\pi}})}{{f(T)}*{\sin\left( {2T} \right)}\quad{\mathbb{d}T}}} = {{\int_{({0\rightarrow{2\pi}})}{\left( {\left( {{\sin\left( {2T} \right)} \pm {0.2*{\sin\left( {2T} \right)}}} \right)*{\sin\left( \quad{2T} \right)}} \right){\mathbb{d}T}}} = {{\int_{({0\rightarrow{2\pi}})}{\sin^{\Cap}2\left( {2T} \right)\quad{\mathbb{d}T}}} \pm {0.2*{\int_{({0\rightarrow{2\pi}})}{\sin^{\Cap}2\left( {2T} \right)\quad{\mathbb{d}T}}}}}}} & \left\lbrack {{equation}\quad 6} \right\rbrack \\{{\int_{({0\rightarrow{2\pi}})}{{f(T)}*{\sin\left( {2T} \right)}\quad{\mathbb{d}T}}} = {\pi \pm {0.2\pi}}} & \left\lbrack {{equation}\quad 7} \right\rbrack\end{matrix}$Comparing the results of the cases of the demodulation of (I) and (II),it is appreciated that influence of the cross-talk of the carrier wavewobble component appears in the demodulation result.

On the other hand, the demodulation by the double cycle of the carrierwave wobble is as follows.∫_((0→2π)) f(T)*sin(T)d T=∫_((0→2π))sin ˆ2(T)d T   [equation 8]∫_((0→2π))sin ˆ2(T)d T=π  [equation 9]∫_((0→2π)) f(T)*sin(2T)d T=π  [equation 10]

In the case of the demodulation of (IV), the following equation 11 isobtained. Additionally, equation 12 is obtained from the above-mentionedequation 9. Additionally, equation 13 is obtained. Thus, equation 14 isobtained. Then, equation 15 is obtained from equation 12 and equation14. $\begin{matrix}{{\int_{({0\rightarrow{2\pi}})}{{f(T)}*{\sin(T)}\quad{\mathbb{d}T}}} = {{\int_{({0\rightarrow{2\pi}})}{\left( {\left( {{\sin(T)} \pm {0.2*{\sin\left( {2T} \right)}}} \right)*{\sin(T)}} \right){\mathbb{d}T}}} = {{\int_{({0\rightarrow{2\pi}})}{\sin^{\Cap}2(T)\quad{\mathbb{d}T}}} \pm {0.2*{\int_{({0\rightarrow{2\pi}})}{{\sin\left( {2T} \right)}\quad*{\sin(T)}{\mathbb{d}T}}}}}}} & \left\lbrack {{equation}\quad 11} \right\rbrack \\{{\int_{({0\rightarrow{2\pi}})}{\sin^{\Cap}2(T)\quad{\mathbb{d}T}}} = \pi} & \left\lbrack {{equation}\quad 12} \right\rbrack \\{{\int_{({0\rightarrow{2\pi}})}{{\sin\left( {2T} \right)}\quad*{\sin(T)}{\mathbb{d}T}}} = {{2*{\int_{({0\rightarrow{2\pi}})}{\sin^{\Cap}2(T)\quad*{\cos(T)}{\mathbb{d}T}}}} = {{2*\left\lbrack {\sin^{\Cap}2(T)\quad*{\sin(T)}} \right\rbrack_{({0\rightarrow{2\pi}})}} - {4*{\int_{({0\rightarrow{2\pi}})}{\sin^{\Cap}2(T)\quad*{\cos(T)}{\mathbb{d}T}}}}}}} & \left\lbrack {{equation}\quad 13} \right\rbrack \\{{\int_{({0\rightarrow{2\pi}})}{{\sin\left( {2T} \right)}\quad*{\sin(T)}{\mathbb{d}T}}} = 0} & \left\lbrack {{equation}\quad 14} \right\rbrack \\{{\int_{({0\rightarrow{2\pi}})}{{f(T)}*{\sin(T)}{\mathbb{d}T}}} = \pi} & \left\lbrack {{equation}\quad 15} \right\rbrack\end{matrix}$

When the result in the recovery of (III) and (IV) is compared, theresult is the same and it turns out that it is not influenced of crosstalk.

Therefore, it can restore to the information, without being influencedof the amplitude change by cross talk by storing the information 2double cycles of the carrier wave wobble.

As mentioned above, in the address signal detection circuit 70, it getsover using the SIN wave signal (fw/2 signal) generated from the 2ndclock signal of Comparing the results of the cases of demodulations of(III) and (IV), the results are the same, and it is appreciated thatthere is no influence of cross-talk received. Thus, by storing theinformation by double cycle of the carrier wave wobble, the informationcan be demodulated without receiving influence of an amplitudefluctuation due to cross-talk.

As mentioned above, in the address signal detection circuit 70, ademodulation is performed using the DIN wave signal (fw/2 signal)generated from the second clock signal of twice the cycle of the carrierwave wobble. The second clock signal needs to synchronize with the firstclock signal of the cycle of the carrier wave wobble used in thesynchronization signal detection circuit 60, the phase thereof beingable to take tow kinds such as 0 degree and 180 degrees.

FIG. 24 is a waveform chart showing waveforms of the output signal ofeach part in a case where the demodulation is performed using the SINwave signal of conditions of the phase 0 degree and the phase 180degrees in the wobble information detection circuit shown in FIG. 22.

(d)-(g) of FIG. 24 show the case of the phase 0 degree, and (h)-(k) ofthe FIG. 24 show the case of the phase 180 degrees.

Comparing both, the polarity of the waveform after the output signal ofthe multiplier is reversed. That is, the polarity of the waveform of theoutput signal from the multiplier in the case of the phase 0 degreeshown in (f) of the figure and the polarity of the waveform of theoutput signal from the multiplier in the case of the phase 180 degreesshown in (j) of the figure area reversed from each other, and also thepolarity of the waveform of the output of the S/H, which is themodulation result, is also reversed between the case of the phase 0degree shown in (g) of the figure and the case where the phase 180degrees shown in (k) of the figure.

Thus, the polarity of the demodulation result changes with thesynchronization state of the first clock signal and the second clocksignal, that is the SIN wave signal (fw signal) and the SIN wave signal(fw/2 signal).

Since the output signal from the S/H is zero other than the double cyclepart of the address area, it cannot make determination only by theoutput signal of the address information detection circuit as to whetherthe polarity is reversed. Therefore, the phase state of the SIN wavesignal (fw signal) and the SIN wave signal (fw/2 signal) needs to bemaintained at certain specified state. In the certain specified states,the beginning of the wobble #0 and the second clock signal, that is, arising or a falling of the SIN wave signal (fw/2 signal) may besynchronized with each other or the rising and the falling may change(toggle state) alternately each time with respect to the beginning ofthe wobble #0.

Next, a description will be given of the recording medium of thefifteenth embodiment and the sixteenth embodiment.

FIG. 25 is an illustration for explaining the format of the fifteenthembodiment and the sixteenth embodiment.

(a)-(c) of FIG. 25 show the arrangement position and the detectedwaveforms of the wobble when a umber of wobbles between the addressareas is set to an odd number of the carrier wave wobble.

(d)-(f) of FIG. 25 shows the arrangement position and the detectedwaveforms of the wobble when a umber of wobbles between the addressareas is set to an even number of the carrier wave wobble.

In the recording medium of the fifteenth embodiment, the carrier wavewobble is set as a reference and the number of wobbles between theaddress areas is defined to be an even number so that the phase of thesecond clock, that is, the SIN wave signal (fw/2 signal), is fixed inthe wobble #0.

As shown in (d) of FIG. 25, when the number of wobbles between theaddress areas is set to an even number, it is the same phase of the SINwave signal (fw/2 signal) each time in the wobble #0 (arrows a1, a2 anda3 in the figure), and, thus, the polarity of the wobble informationsignal is uniquely determined.

On the other hand, in the recording medium of the sixteenth embodiment,the number of wobbles between the address areas is defined to be an oddnumber, and the polarity of the information stored in the address areais recorded after reversed alternately in each of the consecutiveaddress areas.

If the number of wobbles between the address areas is set to be an oddnumber as shown in (a) of FIG. 25, the phase of the SIN wave signal(fw/2 signal) generated based on the second clock signal is reversed, asshown in (c) of FIG. 25, each time the wobble #0 is received (arrows b1,b2 and b3 in the figure).

If it is demodulated in the state, the polarity of the detected addressdemodulation data changes alternately, and it is necessary for a signalprocessing circuit of a subsequent stage to restore the information, forwhich the demodulation data bit (Bit) is reversed every other data,stored in the wobble. Or, the SIN wave signal (fw/2 signal) may bereversed for each address area.

However, both need the complicated processes at the time ofdemodulation. Thus, it is desirable that, in the data stored on therecording medium, the wobble information train is divided based on anumber of information bits (Bits) storable in one address area as aunit, and a bit reverse is made for every other data. Thereby, there isno problem even if the polarity of the SIN wave signal (fw/2 signal) isreversed for each address area due to the number of wobbles between theaddress areas is an odd number.

Moreover, in the recording medium of the seventeenth embodiment, thenumber of wobbles between the above-mentioned synchronization areas isset to be equal to or greater than a sum of the length of the addressarea and the length of the synchronization area by making the carrierwave wobble as a reference.

In the demodulation of the present embodiment, in order to find a wobbleshift early, the phases of the SIN wave signal (fw signal) and the SINwave signal (fw/2 signal) should always be checked irrespective of thenumber of wobbles between the address areas.

This is because the output signal of the address information detectioncircuit becomes 0 in areas other than the address area, anddetermination of the polarity cannot be made.

FIG. 26 is an illustration for explaining an easiest method for checkinga phase state in the wobble information detection circuit of thethirty-second embodiment and the thirty-third embodiment.

The synchronization signal (the output signal of the S/H) is detectedusing the above-mentioned synchronization signal detection circuit 60.

If the level of the binary signal of the SIN wave signal (fw/2 signal)is detected at the timing of the synchronization signal, the phase ofthe SIN wave signal (fw/2 signal) in the wobble #0 is detectable.

Of course, if a relationship between the phases of the SIN wave signal(fw/2 signal) and the second clock signal is determined, the secondclock signal may be used instead of the binary signal.

Since the positional relationship between the synchronization area andthe address area is determined on the format, similar polarity check maybe performed in the vicinity of the address area which delayed byseveral wobbles based on the timing of the synchronization signal.

Since the state will be maintained if it is in the ideal state and ischecked once at the time of starting the demodulation, the polaritycheck of the SIN wave signal (fw/2 signal) explained above does not needto be performed each time in the synchronization area.

However, in practice, the synchronized state is deteriorated for a shorttime due to an external disturbance such as a flaw on the recordingmedium, which may generates a difference in the number of wobblesbetween the address areas. This is referred to as a wobble shift, and ifthe wobble shift is generated, phase relationship between the SIN wavesignal (fw signal) and the SIN wave signal (fw/2 signal) isdeteriorated. Thus, the polarity should be checked for eachsynchronization area each time.

Next, in the recording medium of the eighteenth embodiment, the fourthwobble, which has a cycle twice the cycle of the carrier wave wobble ofwhich phase and generating position is fixed and has a length twice thelength thereof, is arranged in a fourth area remote from thesynchronization area by the carrier wave wobble cycle irrespective ofthe information stored by the wobble.

That is, the wobble portion of double cycle of the carrier wave of whichphase and position are fixed is arranged irrespective of data of thewobble information.

FIG. 27 is a waveform chart showing an example of a wobble form of aformat of the recording medium of the eighteenth embodiment.

A type (Type) A shown in (c) of FIG. 27 is one in which a part 12′ ofthe special wave wobble 12 having a cycle twice the carrier wave wobble,which is not relevant to the wobble information, is continuouslyarranged in front of the special wave wobble 12 having a cycle twice thecarrier wave wobble arranged at #6 and #7 in the address area.

A type (Type) B shown in (d) of FIG. 27 is one in which a part 12′ ofthe special wave wobble 12 having a cycle twice the carrier wave wobble,which is not relevant to the wobble information, is arrangedcontinuously to the synchronization wobble 16 having one cycle of thecarrier wave wobble arranged at #1 in the address area.

A type (Type) 1 shown in (b) of FIG. 27 is also shown in FIG. 12, and isa wobble form used in the above description.

Although the generation of a wobble shift can be detected if it isshifted by 1 wobble according to the above-mentioned method of checkingthe phase of the SIN wave signal (fw/2 signal), the detection cannot bemade since the comparison result is correct if it is shifted by 2wobbles.

Thus, by arranging the wobble (the special wave wobble) of double cycleof the carrier wave wobble, which is not relevant to the wobbleinformation, with fixed position and phase in reference to thesynchronization area, the polarity of the wobble information can bedetermined even if a wobble shift is generated. It should be noted that,as indicated in the type A and type B, the position to add the doublecycle is preferably in the vicinity of the synchronization area or theaddress area, and preferably has a length of about 1-2 wobbles of thecarrier wave wobble so that is does not give influences to theextraction of the carrier wave wobble component.

FIG. 28 is a waveform chart showing a signal waveform when demodulatingthe wobble form of the type A shown in FIG. 27. In the figure, solidbold lines indicate the case of data 0 (Data_0), and dotted bold linesindicate the case of the data 1 (Data_1).

The wobble number and the wobble number expected are the same asmentioned above. With respect to the demodulation with the SIN wavesignal (fw signal), it is the same as the above mentioned except for theoutput signal of the S/H being zero level in a portion of double cycle,which is added newly, and a more description will not be given.

(h)-(k) of FIG. 28 shows the waveforms of the output signals of eachpart of the wobble information detection circuit of FIG. 22 when thephase of the SIN wave signal (fw/2 signal) is 0 degree.

(l)-(o) of FIG. 28 shows the waveforms of the output signals of eachpart of the wobble information detection circuit of FIG. 22 when thephase of the SIN wave signal (fw/2 signal) is 180 degrees.

The phase is 0 degree normally, but it is considered that is becomes 180degrees due to generation of a wobble shift.

Originally, if the phase is 0 degree, the output signal of S/H of theaddress area has a signal level of a positive side as indicated by abold line in (k) of FIG. 25.

However, if the phase is 180 degrees, it becomes a level of an oppositenegative side and a polarity is reversed, and the output signal of theS/H of the address area has a signal level on the negative side as shownin (o) of FIG. 25. In this case, an erroneous detection will be madeunless detection is made that it is reversed.

However, since in the result of demodulation of the double cycle portionirrelevant to the added wobble information, the signal level isdetermined to be on the negative side when the phase is 0 degree and onthe positive side when the phase is 180 degrees, this indicates that thephase of the SIN wave signal (fw/2 signal) is reversed.

Moreover, although the phase of the SIN wave signal (fw/2 signal)becomes 0 degree when 2 wobble shift is made, the wobble number expectedand the position of wobble demodulation data shift. However, since aknown data bit (demodulation result of the double cycle portion, whichis irrelevant to the wobble information) is detected in a head of thedemodulated data, the wobble information may be demodulated with theknown data bit as a trigger. Thus, the signal level of the double cycleportion, which is irrelevant to the wobble information can be detected,and the polarity and the position of the demodulation result of thewobble information portion can be determined.

FIG. 29 is a block diagram showing a structure of an informationrecording and reproduction apparatus of the thirty-sixth embodiment andthe thirty-seventh embodiment.

The information recording and reproduction apparatus can be divided intoan optical pickup 90 which carries an optical system, a motor 100 formoving the optical pickup 90 and rotating a recording medium 107, andvarious kinds of electric circuits. Mounted on the optical pickup 90 area laser light source 91, optical parts which lead the light generated bythe laser light source 91 to each element, an object lens 92 which makesa spot of the light on the recording medium 107, and an actuator 93which controls the position of the object lens 92 to make the spotfollow a desired position.

Moreover, there are the following electric circuits.

There are a laser drive circuit 101 which determines a current andwaveform to cause the laser light source 91 to emit a light based on therecording information, an operation circuit 102 which performs anphotoelectric conversion and operations on signals including a wobblesignal, an RF signal and a servo signal from a reflection signal fromthe recording medium 107 and received by a light-receiving element 94,and an RF process circuit 103 which detects reproduction informationbased on the RF signal. The reproduction information is transferred tothe demodulation circuit (since it is well-known, illustration isomitted), and is changed into user data.

The wobble information detection circuit 104 corresponds to the wobbleinformation detection circuit mentioned above, and the wobbleinformation is input and the clock signal and the information such asaddress information stored in the wobble are detected. the servo signalperforms various kinds of operations by a servo signal detection circuit105, extracts positional information of the spot by a servo processingcircuit 106, and causes to the motor 100, the optical pickup 90 and theactuator 93 to operate so as to cause the spot to follow a desiredposition.

FIG. 30 is an illustration for explaining the detection of the wobblesignal from the light-receiving element 29 to the arithmetic circuit 102in FIG. 29.

As shown in (b) of the figure, the light-receiving surface is divided byat least two (areas 94 a and 94 b indicated by A and B in the figure)and the dividing line 110 is parallel to the track 2 shown in (a) of thefigure. Then, a difference between both the light-emitting elements 49 aand 49 b is calculated by the arithmetic circuit 102 so as to detect thewobble signal.

In the format of the recording medium of the embodiments of the presentinvention, the synchronization signal and the information signal aredetected using the SIN wave signal (fw signal) of the carrier wave cyclefor detecting the synchronization area (the third area) and the SIN wavesignal (fw/2 signal) of the double cycle (½ frequency) of the carrierwave for detecting the address area (the second area).

These SIN signals may be the clock signal generated from the carrierwave component obtained from the wobble signal, or may be produced basedon the clock signal. When the SIN wave signal (fw/2 signal) of doublecycle used for detection of the address area is synchronized with thewobble signal, if the phase 0 point is considered as a reference, thephase of the SIN wave signal (fw/2 signal) of double cycle can takeeither 0 degree or 180 degrees. It has a characteristic in which thepolarity of the information (data) demodulated from the address areaaccording to the phase state is determined.

That is, the polarity of the data cannot be determined unless the phasestates of the wobble signal and the SIN wave signal (fw/2 signal) ofdouble cycle are maintained in a state based on a certain definition,and an accurate detection of information cannot be performed. Thus, in astable condition, the phases of the phase states of the wobble signaland the SIN wave signal (fw/2 signal) of double cycle are maintained ina state based on a certain definition.

Moreover, there may be a case in which the wobble signal cannot bedetected, although it is a short period of time, due to a small flaw onthe recording medium or an abrupt detection circuit noise.

In such a case, there may be a case in which the number of wobblesignals and the number of clock signals to be detected in a fixed perioddoes not match.

For example, if the interval of the synchronization areas corresponds to60 wobbles, the clock signal is slightly gains when the wobble is notdetected, and the next synchronization area is at a time when thedetected clock signal is fifty-ninth. Such a matter in which the numberof wobble signals and the number of clock signals to be detected in afixed time do not match is referred to as a wobble shift.

Of course, if there is a large flaw on the recording medium, since thetracking serve or the like works off and it is offset from the originalaccess position, there is simply no justification as it is needed torestart from generation of the clock. Thus, in the present embodiment,it can be coped with the case where the number of wobbles and the numberof clocks are different from each other eve if the tracking servo ifnormal and an access is made continuously to the correct track.Additionally, the synchronization signal to be inserted for each brakepoint of information is also defined.

According to the recording medium, the wobble cycle detection method,the wobble information detection method, the wobble informationdetection circuit, and the information recording and reproductionapparatus of the present embodiment, the wobble format is made toacquire a high S/N ratio of the information demodulation signal and ahigh position accuracy so that restoration is easily made if the wobbleshift is generated and a stable information detection can be performednot only in a stable condition.

Thus, according to the recording medium of the first embodiment,information can be detected with high quality, and restoration ofreliable information can be enabled.

Moreover, according to the recording medium of the second embodiment,since the demodulation signal having the highest signal S/N ratio isacquired, restoration of reliable information can be enabled.

Further, according to the recording medium of the third embodiment,information is included in the phase and the generating position, thehigh quality demodulation signal is acquired, and restoration ofreliable information can be enabled. Moreover, an amount of informationcan be increased without increasing the special wave wobble component tocross talk.

Moreover, according to the recording medium of the fourth embodiment,since the demodulation signal having the highest signal S/N ratio isacquired, restoration of reliable information can be enabled.

Further, according to the recording medium of the fifth embodiment,since the zone separation with the record information signal (frequencyhigher than the carrier wave) used as a noise component to the wobblesignal can be clarified, the good wobble signal is detectable. Moreover,the clock signal used for the demodulation can be acquired easily fromthe carrier wave component.

Moreover, according to the recording medium of the sixth embodiment, thezone separation with the record information signal is also attainedwhile securing a large amount of information stored in the wobble.

Furthermore, according to the recording medium of the seventhembodiment, since the special wave wobble signal is always completed inunit of 1 cycle and does not have a DC component, the detection circuitis easily formed.

Moreover, according to the recording medium of the eighth embodiment,new information, i.e., the synchronization information, can be stored inthe wobble without giving bad influences to reproduction of recordedinformation by the synchronization wobble.

Furthermore, according to the recording medium of the ninth embodiment,while distinction from the special wave wobble is easy, the structure ofthe detection circuit can be almost the same as the detection of thespecial wave wobble, and further there is no influence given to thedetection of the special wave wobble.

Moreover, according to the recording medium of the tenth embodiment, theposition of the special wave wobble can be pinpointed correctly,detection of high-quality and reliable information can be performed.

Furthermore, according to the recording medium of the eleventhembodiment, since a distance to the special wave wobble is increasedwhen the synchronization signal is pulled in and distinction thereof iseasy, the pull-in can be carried out at high speed. Moreover, since thewobble cycle signal disordered immediately after passing thesynchronization area is restored in the interposed carrier wave area,the clock signal generated from the wobble cycle signal can be keptstable.

Moreover, according to the recording medium of the twelfth embodiment,the carrier wave area is acquired in which the wobble cycle signalextracted by the band pass filter is sufficiently recovered after it isdisordered in the synchronization area, and the clock signal generatedfrom the wobble cycle signal can be kept stable.

Furthermore, according to the recording medium of the thirteenthembodiment, information can be stored without giving a large influenceto the carrier wave component extraction for clock generation.Additionally, the detection of the wobble shift can be performedfrequently.

Moreover, according to the recording medium of the fourteenthembodiment, pinpointing of the generating position of the special wavewobble can be carried out easily, and the break point of the informationcan also be discovered easily.

Furthermore, according to the recording medium of the fifteenthembodiment, the phase of the reference signal (second clock) used fordemodulation is always fixed, and the polarity of the demodulationsignal is determined uniquely.

Moreover, according to the recording medium of the sixteenth embodiment,the phase of the reference signal (second clock) used for demodulationshifts by 180 degrees for each second area, the data on the recordingmedium (media) is processed in consideration of demodulation data beingreversed, there is no need to carry out a reversal process of thereference signal in the demodulation circuit and data processing such asreversing the demodulated data alternately, and information detectioncan be performed easily.

Moreover, according to the recording medium of the seventeenthembodiment, a rate of disordering of the carrier wave cycle in themodulation part can be sufficiently reduced, and a stable referencesignal for demodulation can be obtained.

Moreover, according to the recording medium of the eighteenthembodiment, even if a wobble shift of equal to or more than two wobblesis generated, exact demodulated data can be restored without causingerroneous detection of data by mistaking the polarity.

Furthermore, according to the recording medium of the nineteenthembodiment, pull-in of synchronization can be carried out at high speed,and reliability of informational can also be raised.

Moreover, according to the recording medium of the twentieth embodiment,the stability of the reference signal (clock) for demodulation can beacquired.

Furthermore, according to the recording medium of the twenty-firstembodiment, pull-in of synchronization can be carried out at high speed,and reliability of informational can also be raised.

Moreover, according to the recording medium of the twenty-secondembodiment, the stability of the reference signal (clock) fordemodulation can be acquired.

Furthermore, according to the recording medium of the twenty-thirdembodiment, distinction of two kinds of synchronization wobbles for canbe determined easily, and high-speed and exact pull-in ofsynchronization can be performed.

Moreover, according to the wobble cycle detection method of the 24thembodiment, the clock can be kept stable without disordering the wobblecycle signal also in the area in which the phase differs from thecarrier wave by 180 degrees. Moreover, since the second area and thethird area can be brought close to each other, there is no mistaking theposition of the second area due to a shift in the wobble numbergenerated by external disturbance or the like.

Furthermore, according to the wobble information detection method of thetwenty-fifth embodiment, the information stored in the wobble of therecording medium of the first embodiment and the second embodiment isdetectable.

Moreover, according to the wobble information detection method of thetwenty-sixth embodiment, the information stored in the wobble of therecording medium of the third embodiment and the fourth embodiment isdetectable.

Furthermore, according to the wobble information detection method of thetwenty-seventh embodiment, the information stored in the wobble of therecording medium of each of the above-mentioned embodiments isdetectable.

Moreover, according to the wobble information detection method of thetwenty-eighth embodiment, the information stored in the wobble of therecording medium of the above-mentioned eighth embodiment and after thatis detectable.

Furthermore, according to the wobble information detection method of thetwenty-ninth embodiment, high-quality and reliable wobble information isdetectable from the above-mentioned recording medium of the thirdembodiment and fourth embodiment.

Moreover, according to the wobble information detection circuit of thethirtieth embodiment, the information stored in the wobble of therecording medium of each of the above-mentioned embodiments isdetectable.

Furthermore, according to the wobble information detection circuit ofthe thirty-first embodiment, the information stored in the wobble of therecording medium of the above-mentioned eighth embodiment and after thatis detectable.

Moreover, according to the wobble information detection circuit of thethirty-second embodiment and the thirty-fourth embodiment, the phase andthe polarity of the reference signal of double cycle used fordemodulation of the address area can be uniquely determined, and thepolarity of the demodulated data can be maintained in a desiredpolarity.

Furthermore, according to the wobble information detection circuit ofthe thirty-third embodiment and the thirty-fifth embodiment, exactdemodulated data can be restored without erroneous detection of data bymistaking the polarity even when a wobble shift is generated.

Moreover, according to the information record playback equipment of thethirty-sixth embodiment, demodulation of good wobble information can beperformed, and a stable access performance can be obtained due to highreliability of the address information, etc.

Furthermore, according to the information record playback equipment ofthe thirty-seventh embodiment, since the wobble information with respectto the recording medium is high quality and smooth pull-in ofsynchronization can be done, high-speed, high-density, stable recordingand reproduction can be performed.

INDUSTRIAL APPLICABILITY

The recording medium according to the present invention is alsoapplicable to a recording media other than the above-mentioned opticaldisc. Moreover, the wobble cycle detection method, the wobbleinformation detection method, the wobble information detection circuit,and the information recording and reproducing apparatus are applicablealso in personal computers such as a desk top personal computer and anotebook personal computer.

1. A recording medium characterized in that a track is divided into afirst area that is continuously wobbled by a first wobble of a specificcarrier wave cycle, and a second area that is wobbled by a second wobblethat has a cycle different from said first wobble and a phase determinedin response to data 0 and data 1 of information stored by a wobble. 2.Recording medium according to claim 1, wherein said second wobble isassigned to phases that are different by 180 degrees, respectively, inresponse to the data 0 and the data 1 of the information stored by thewobble.
 3. A recording medium characterized in that a track is dividedinto a first area that is continuously wobbled by a first wobble of aspecific carrier wave cycle, a second wobble that has a cycle differentfrom said first wobble and a phase determined in response to data 0 anddata 1 of information stored by a wobble, and a second area in which agenerating position of said second wobble is also determined in responseto said information.
 4. The recording medium according to claim 3,wherein a relative generating position of said second wobble is changedby a length of the second wobble in accordance with data 0 and data 1 ofthe information stored by the wobble, and are assigned to phases thatare different from each other by 180 degrees.
 5. The recording mediumaccording to claim 1, wherein a cycle of said second wobble is anintegral multiple of a carrier wave cycle.
 6. The recording mediumaccording to claim 1, wherein a cycle of said second wobble is twice acarrier wave cycle.
 7. The recording medium according to claim 1,wherein a length of said second wobble is twice a carrier wave cycle. 8.The recording medium according to claim 1, wherein a third areacontaining a third wobble is formed, the third wobble beingdistinguishable from said first wobble and said second wobble.
 9. Therecording medium according to claim 8, wherein the third wobble has thecarrier wave cycle and has a form having a phase different from thefirst wobble by 180 degrees.
 10. The recording medium according to claim8, wherein said third area is arranged immediately before said secondarea.
 11. The recording medium according to claim 8, wherein said firstarea is arranged immediately before said third area.
 12. The recordingmedium according to claim 11, wherein a length of the first areaarranged immediately before said third area is equal to or more thanfive times the carrier wave cycle.
 13. The recording medium according toclaim 8, wherein said third area is arranged at a fixed interval, andsaid second area is arranged intermittently and adjacent to said thirdarea.
 14. The recording medium according to claim 13, wherein a lengthof the third area located adjacent to said second area and a length ofthe third wobble of the third area arranged independently and separatelyfrom the second area are different.
 15. The recording medium accordingto claim 1, wherein a number of wobbles between said second wobbles isan even number on the basis of the carrier wave as a reference.
 16. Therecording medium according to claim 1, wherein a number of wobblesbetween said second areas is an odd number on the basis of the carrierwave, and a polarity of the information stored in the second area isreversed alternately for each second area and recorded.
 17. Therecording medium according to claim 1, wherein a number of wobblesbetween said third areas is equal to or more than ten times a length ofa sum of a length of the second area and a length of the third area onthe basis of the carrier wave as a reference.
 18. The recording mediumaccording to claim 8, wherein a fourth wobble is arranged in a fourtharea located at a position separate from said third area by apredetermined carrier wave cycle, a phase and the a generating positionof the fourth wobble being fixed irrespective the information stored bythe wobble, the fourth wobble having a twice cycle and a twice length ofthe carrier wave cycle.
 19. A recording medium characterized in that atrack is divided into a first area continuously wobbled by a firstwobble of a specific carrier wave wobble, a third area containing athird wobble that has the same cycle as said first wobble and has aphase different from said first wobble by 180 degrees, the third areahaving a length four times said specific carrier wave cycle, and asecond area including a second wobble having a twice cycle and a twicelength of said specific carrier wave and assigned to phases different by180 degrees, respectively, in response to data 0 and data 1 ofinformation stored by a wobble, wherein said third area is arrangedimmediately before or adjacent to said second area.
 20. The recordingmedium according to claim 19, wherein a number of wobbles between saidthird areas is equal to or greater than 60 on the basis of the carrierwave as a reference.
 21. A recording medium characterized in that atrack is divided into a first area continuously wobbled by a firstwobble of a specific carrier wave wobble, a third area containing athird wobble that has the same cycle as said first wobble and has aphase different from said first wobble by 180 degrees, the third areahaving a length four times said specific carrier wave cycle, and asecond area including a second wobble having a twice cycle and a twicelength of said specific carrier wave, a relative generating positionthereof being a position distant by twice the carrier wave cycle, thesecond wobble being assigned to phases different by 180 degrees,respectively, in response to data 0 and data 1 of information stored bya wobble, wherein said third area is arranged immediately before oradjacent to said second area.
 22. The recording medium according toclaim 21, wherein a number of wobbles between said third areas is equalto or greater than 80 on the basis of the carrier wave as a reference.23. The recording medium according to claim 19, wherein the third wobbleof said third area has a one-cycle length or four-cycle length of saidspecific carrier wave period, and the third wobble of said third areaarranged immediately before or adjacent to said second area has saidone-cycle length and others have said four-cycle length.
 24. A wobblecycle detection method characterized by multiplying wobble signals ofthe same signal obtained from wobbling of a track formed on a recordingmedium each other by a multiplier, and inputting a signal obtained by anoperation of the multiplication into a band pass filter of which a passband is set to about twice a frequency of a carrier wave so that a cycletwice an output signal of the band pass filter is set to a cycle of thecarrier wave of the wobble signal.
 25. A wobble information detectionmethod characterized by a carrier wave processing procedure ofextracting a frequency component of the first wobble from the first areaof the recording medium according to claim 1, a special wave processingprocedure of extracting a phase information component of the secondwobble from the second area of said recording medium, an informationdetecting procedure of detecting the information stored by the wobblefrom the phase information component extracted by said special waveprocessing procedure based on the frequency component extracted by saidcarrier wave processing procedure.
 26. A wobble information detectionmethod characterized by a carrier wave processing procedure ofextracting a frequency component of the first wobble from the first areaof the recording medium according to claim 8, a special wave processingprocedure of extracting a phase information component of the secondwobble from the second area of said recording medium, a synchronizationprocessing procedure of extracting a phase information component of thethird wobble of the third area of said recording medium, and aninformation detecting procedure of detecting the information stored bythe wobble from the phase information components extracted by saidspecial wave processing procedure and said synchronization processingprocedure based on the frequency component extracted by said carrierwave processing procedure.
 27. A wobble information detection methodcharacterized by a carrier wave processing procedure of extracting afrequency component of a first wobble from the first area of therecording medium according to claim 1 and generating a clock of at leasttwice the specific carrier cycle, a special wave processing procedure ofextracting a phase information component of the second wobble from thesecond area of said recording medium based on at least the clock oftwice said specific carrier wave cycle, and an information detectingprocedure of detecting the information stored by the wobble from thephase information component extracted by the special wave processingprocedure.
 28. A wobble information detection method characterized by acarrier wave processing procedure of extracting a frequency component ofa first wobble from the first area of the recording medium according toclaim 8 and generating clocks of said specific carrier cycle and twicesaid specific carrier frequency, a special wave processing procedure ofextracting a phase information component of the second wobble from thesecond area of said recording medium based on at least the clock oftwice said specific carrier wave cycle, a synchronization processingprocedure of extracting a phase information component of the thirdwobble from the third area of said recording medium based on the clockof said specific carrier wave cycle, and an information detectingprocedure of detecting the information stored by the wobble from thephase information component extracted by said special wave processingprocedure in said second area of which position is specified based onthe phase information component extracted by the synchronizationprocessing procedure.
 29. The wobble information detection methodaccording to claim 27, wherein both a first demodulation and a seconddemodulation are performed in said second area, the first demodulationfor detecting a phase or a frequency of the a wobble signal based on theclock of said specific carrier wave cycle, the second demodulation fordetecting a phase or a frequency of the wobble signal based on the clockof twice said specific carrier wave cycle, and determines the data 0 andthe data 1 of the information stored by the wobble based on results ofboth said demodulations.
 30. A wobble information detection circuitcharacterized by comprising a wobble cycle detection circuit thatdetects a cycle of the carrier wave from a wobble signal obtained fromwobbling of the track formed on the recording medium according to claim1, a clock signal generation circuit that generates a second clocksignal of a twice cycle of the carrier wave based on the cycle of thecarrier wave detected by the wobble cycle detection circuit, and aspecial wave wobble detection circuit that indicates a position or aphase of the second wobble of said second area based on said secondclock signal.
 31. A wobble information detection circuit characterizedby comprising a wobble cycle detection circuit that detects a cycle ofthe carrier wave from a wobble signal obtained from wobbling of thetrack formed on the recording medium according to claim 8, a clocksignal generation circuit that generates a first clock signal of a cycleof the carrier waver and a second clock signal of a twice cycle of thecarrier wave based on the cycle of the carrier wave detected by thewobble cycle detection circuit, a synchronization signal detectioncircuit that detects a synchronization signal indicative of the thirdwobble of said third area based on said first clock signal, a positionsignal generation circuit that generates a position signal indicative ofsaid second area on the basis of said synchronization signal as areference, and a special wave wobble detection circuit that indicates aposition or a phase of the second wobble of said second area based onsaid second clock signal in accordance with said position signal. 32.The wobble information detection circuit according to claim 31, whereina phase or a polarity of said second clock signal is detected for eachgeneration of said synchronization signal so as to match said secondclock signal to a desired phase or polarity in accordance with a resultthereof.
 33. The wobble information detection circuit according to claim31, wherein a phase or a polarity of said second clock signal isdetected for each generation of said synchronization signal so as todetermine a polarity of data demodulated from said second area inaccordance with a result thereof.
 34. The wobble information detectioncircuit according to claim 31, wherein a fourth wobble of said fourtharea in said recording medium is demodulated based on said second clocksignal so as to match said second clock signal to a desired phase orpolarity in accordance a result thereof.
 35. The wobble informationdetection circuit according to claim 31, wherein a fourth wobble of saidfourth area in said recording medium is demodulated based on said secondclock signal so as to determine a polarity of data demodulated from saidsecond area in accordance with a result thereof.
 36. An informationrecording and reproduction apparatus characterized by being mounted withthe wobble information detection circuit according to claim 30, whereinan access is made to a target position of said recording medium based oninformation detected by the wobble information detection circuit so asto perform recording or reproduction of information on said recordingmedium.
 37. An information recording and reproduction apparatuscharacterized by comprising an optical pickup that irradiate a laserlight onto the recording medium according to claim 1 and detects areflection signal from said recording medium, a rotational drivemechanism part that rotationally drives said recording medium, a servocontrol system that controls a position of said optical pickup and arotation of said recording medium by said rotational drive mechanismpart based on detection information detected by said optical pickup, andinformation detecting means for detecting a position signal necessaryfor the servo control system and information stored in said recordingmedium based on the detection signal detected by said optical pickup,wherein the information detected by said information detecting means isdetected so as to perform recording and reproduction of information onsaid recording medium.